ELC Audio Engineering and Cochlear Concepts are currently
developing a new cochlear implant (CI) processing strategy and
active-circuit electrode array. For additional information,
please visit Cochlear Concepts' FAQs page via
cochlearconcepts.com. Cochlear Concepts also develops
controlled, real-world auditory environments (with
occasional video stimuli) for speech & hearing science
research. It is our belief that the external validity of
investigations regarding cochlear implants, hearing aids,
and hearing protection devices will be enhanced by the use
of periphonic systems that utilize Ambisonics (not to be
confused with ambiophonics). High-order Ambisonics is an
appropriate technology for testing hearing aids and cochlear
implants because the sound field is reproduced correctly in
the middle of the loudspeaker array--as opposed to
wave-field synthesis (WFS), where the error is spread around
the whole area of reproduction. Our Ambisonic recordings
were made in a variety of establishments, to include "quiet"
restaurants and coffee cafés. Recordings of quieter
establishments are useful for studying cochlear implant
processor strategies because the judicial use of moderate
background noise allows the researcher to maintain positive
signal-to-noise ratios (e.g., + 10 dB) that accurately
represent real-world scenarios. The recordings were made
using a specially designed Ambisonic microphone to capture
each sound sources' direction (in the horizontal and
vertical directions!) as well as natural reverberation. The
raw (A-format) recordings were 24 bit, 96 kS/s digital
recordings. Many of the B-format files and multi-channel
stimulus files have been dithered to 16 bit for portability.

Future postings on this site
will include information on how ELC Audio Engineering / Cochlear Concepts re-creates soundfields in the laboratory--just as they existed in the
real world. In the meantime, interested parties are
encouraged to read related articles from
The Hearing Journal
and
Acta Acustica united with Acustica. It should be noted,
however, that our Ambisonic surround system incorporates live
recordings in addition to auralization techniques utilizing
room impulse responses (RIRs).
Cochlear Concepts will also be providing information on the
development of ergonomic participant interfaces with
embedded microcontrollers. The microcontroller-based
interfaces are used to automate stimuli presentation and
data acquisition for experiments performed in our virtual
listening environments. While this website is new (last
update: December, 2011), Cochlear Concepts will soon be
adding links to our research, articles on Ambisonics (with
permission from their respective authors and publishers),
and the mathematics behind spherical harmonics. Note:
Spherical harmonics should not be confused with the usual
definition of "harmonics" that we often encounter while
discussing sound or music. Spherical harmonics are, in a
nutshell, the angular portion of a set of solutions to Laplace's equation, first introduced by Pierre Simon de
Laplace (click
here for Wikipedia link to spherical
harmonics). Ambisonics, largely developed by the late
Michael Gerzon (Professor of Mathematics, University of
Oxford), is mathematically based on spherical harmonics.

Many thanks to Dr. Bengt-Inge Dalenbäck of CATT-Acoustic (www.catt.se)
and Dr. Pauli Minnaar of Oticon (www.oticon.com) for their
insight, suggestions and kind words. A brief blurb about
yours truly that appeared in The Hearing Journal can be seen
here (I appear on pages 14-15). A draft of my paper titled
"Ecological Considerations for Cochlear Implant Research"
can be accessed
here. A PowerPoint presentation that
delineates this paper and includes photos can be accessed by
clicking
here (the file is currently titled psy591 ecarmich).

A short list of articles by Eric L.
Carmichel (author of this site) can be viewed
here. Please click
CV for my
curriculum vitae. I can be reached at
eric@elcaudio.com.